Restore shm_reclen as an alias for vsl_reclen

Fixes #2307

bin/varnishd/mgt/mgt_param_tbl.c

@@ -144,6 +144,12 @@ struct parspec mgt_parspec[] = {
 		MEMPOOL_TEXT,
 		0,
 		"10,100,10", ""},
+	{ "shm_reclen", tweak_vsl_reclen, &mgt_param.vsl_reclen,
+		"16b", NULL,
+		"Old name for vsl_reclen, use that instead.",
+		0,
+		"255b",
+		"bytes" },
 
 	{ NULL, NULL, NULL }
 };

bin/varnishtest/tests/r02307.vtc

+varnishtest "shm_reclen alias for vsl_reclen"
+
+varnish v1 -cli "param.set shm_reclen 42"
+varnish v1 -cliexpect 42b "param.show vsl_reclen"

include/tbl/params.h

@@ -969,6 +969,8 @@ PARAM(
 	/* func */	NULL
 )
 
+#if 0
+/* actual location mgt_param_tbl.c */
 PARAM(
 	/* name */	shm_reclen,
 	/* typ */	vsl_reclen,
@@ -982,6 +984,7 @@ PARAM(
 	/* l-text */	"",
 	/* func */	NULL
 )
+#endif
 
 PARAM(
 	/* name */	shortlived,